Electrical system providing sequence operation



Feb. 12, 1935. c. v 5. sun's ELECTRICAL SYSTEM PROVIDING SEQUENCEOPERATION Original Filed Aug. 30

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k DwLL 3b utwtowmso Inventor:

m W 8 m U 0 t H t w A n .s w H h C Patented Feb. 12, 1935 UNITED STATESPATENT OFFICE ELECTRICAL SYSTEM PROVIDING SEQUENCE OPERATION Chauncey G.Suits, Schenectady, N. Y., assignor to General Electric Company, acorporation of New York 11 Claims.

My invention relates to electrical systems containing a plurality ofunits which operate in a definite sequence. More particularly it relatesto an electrical system comprising a series of lamps which are operatedsuccessively either to become illuminated or extinguished in apredetermined sequence. My present invention is a further development ofthe system disclosed and claimed in my copending application, Serial No.582,801, filed December 23, 1931, and assigned to the same assignee asmy present application.

In that system of sequence operation of a plurality of units, thecircuit of the last unit of a group comprising a series was connectedback to control the circuit of the first unit of the series, whereby theunits of the series were alternately energized and deenergized.

In certain cases, as for example in the operation of electric signswhere the units are electric lamps, it is sometimes desirable that agreater time delay or a pause shall occur following the operation of thelast unit of the series. A greater time delay also is desirable in caseswhere the series comprises so few units that the delay apparatusemployed therein between units provides insufiicient time for the units,particularly where they are incandescent lamps, to completely respond toone condition before they are subjected to the opposite condition. Forexample, if the series comprises only four or five lamps theenergization and deenergization of the lamps may succeed each other sorapidly that the filaments cannot fully respond thereto.

My present invention has for its object the provision of an improvedsystem of the above described character whereby a greater time delay iseffected between an operation of the last unit of the series and anopposite operation of the first unit of the series. A further object ofmy invention is the provision for such time delay without causing anynoticeable fiicker in the units incident to the operation of the delayproducing means.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing and its scope will bepointed out in the appended claims.

Referring to the drawing Fig. l is a circuit diagram of one embodimentof my invention; Figs. 2 and 3 are fragmentary diagrams illustratingmodifications of what is shown in Fig. 1; Fig. 4 is a curve illustratingthe operation of the arrangement shown in Fig. 3; Fig. 5 shows a furthermodified form; and Figs. 6 and 7 illustrate two forms of saturable corereactor which may be used in the apparatus shown by Figs. 1, 2 and 3.

In the drawing an alternating current supply circuit is shown at 1 and 2which may be connected with any suitable source of alternating currentillustrated at 3, which for example may be a 110 volt, 60 cycle source.Connected across the supply circuit 1 and. 2 is a series of branchcircuits, each containing a load device, such as an incandescent lamp,represented by 10 4, 5, 6 and 7. Such load devices may for example bebeacon or field border lamps at an airport, the lamps of an electricsign or any other load devices which it is desired to have operate in acertain sequence. In each branch 15. circuit and in series with the loaddevice of that circuit is the alternating current winding 9 of asaturable core reactor 10 having a direct current saturating winding 11.The winding 11 of each of these reactors is with the exception 20 of thereactor in the first branch circuit shown connected across the lamp ofthe preceding branch through a full wave rectifier, which may be of wellknown construction, represented at 12. In the first branch circuit ofthe series is 25 the starting switch 13. The rectifier 12 associatedwith the reactor of the first branch circuit has one terminal connectedthrough a resistor with the supply line 1 and the other terminalconnected through conductor 12' and the contacts 30 of the relay 14 withthe supply line 2. The winding 15 of relay 14 is connected across the reactor 10 of the last branch circuit, whereby when the impedance ofreactor 10 increases due to the desaturation of its core the relay isoperated to 35 close its contacts l4 and conversely when the impedanceof the reactor decreases due to the saturation of its core, the relaybecomes deenergized sufficiently to allow the relay to move to opencircuit position. Arranged in shunt with 40 the winding 15 of relay 14is the capacitor 16 whoseca'pacitance has such a value that theimpedance offered by the winding 15 and the capacitor 16 is the samewhether the relay is in closed or open circuit position. Thus the ef- 45feet of the armature of the relay in varying the inductance of winding15 in response to its movement is completely compensated by thecapacitor 16.

, The operation of this form of my invention is 50 as follows: Supposingthe lamps 4, 5, 6 and '1 of the series are dark and closing of theswitch 13 causes lamp 4 to be illuminated inasmuch as the reactor 10 inseries therewith being saturated by winding 11 oflers a minimumimpedance. The v lamps 5, 6 and 7 remain dark inasmuch as the reactor 10in series with each being unsaturated offers a maximum impedance. Assoon as current fiows through lamp 4 of the first branch, the potentialdrop across that lamp causes the reactor 10 of the second branch tobecome saturated whence the impedance oifered by that reactor drops tosuch a value that lamp 5 is illuminated. In a similar manner each lampof the series successively becomes illuminated, the operation of eachreactor producing a predetermined time delay so that the lamps becomeilluminated in a definite sequence. When lamp 7 of the last branchbecomes illuminated due to the decrease in impedance of the reactor inseries therewith, relay 14 drops open and thereby cuts of! the supply ofsaturating current to reactor 10 of the first branch of the series. Theimpedance of this reactor accordingly rises to such a value that lamp 4is extinguished. In a similar manner each succeeding lamp of the seriesbecomes extinguished. In addition to the time delay produced by thereactor 10 of the first branch circuit between the operation of lamp 7and the lamp 4, the efiect of the relay 14 is to introduce an additionaltime delay, the amount of the delay being governed by the spacing of thecontacts and the construction of the relay.

In certain cases I have found that the change in the magnetic circuit ofthe relay due to the operation thereof caused an undesirable flicker inthe lamps. This however I am able to avoid by the use of the capacitor16 in shunt with the winding of the relay, this capacitor as has beenpointed out above having such a value that the total impedance offeredby the relay winding and the capacitor is substantially the same whetherthe relay is in open or closed circuit position.

In the modified form of my invention illustrated by Fig. 2 the relaywinding 15 is supplied by rectified current from the rectifier 17connected across the reactor 10 of the last branch. With thisarrangement I have found that it is unnecessary to provide a capacitoracross the relay winding to avoid flicker of the lamps since thetransient current which flows when the relay armature changes positionis dissipated in the relay winding now in the rectifier circuit in sucha manner that the alternating current impedance of the combination issubstantially unaltered by the movement of the relay armature. Thecircuit otherwise is the same as in Fig. 1.

In the modified form illustrated by Fig. 3 the additional time delaybetween an operation of the lamp in the last branch circuit and anopposite operation of the lamp in the first branch circuit is eflectedby the use of the resonant circuit 20 which has a non-linear volt-amperecharacteristic. This circuit is shown including the reactor 21 andcapacitor 22 connected in series and bridged across the reactor 10 ofthe last branch circuit. The rectifier 12 of the first branch circuit inthis case is connected by conductor 12' with the non-linear resonantcircuit between the reactor and the capacitor thereof. For the purposeof preventing a fiicker of the lamps due to the operation of thenon-linear resonant circuit, I employ the capacitor 23 in shunttherewith. It is well known that when the voltage applied to anon-linear resonant circuit is gradually increased the circuit becomesresonant at a certain voltage and the current fiow in the circuit atthis voltage suddenly rises and with further increase in voltagecontinues to rise at a less rapid rate, the point of sudden rise ofvoltage being known as the resonant voltage. It is also well known thatif the applied voltage is gradually decreased a voltage will be reachedat which the current suddenly decreases, which voltage is known as thedissonant voltage. This phenomenon is illustrated by way of example inFig. 4 which shows the voltage-current curve of a nonlinear resonantcircuit. In this figure, curve 25 represents the increase in current dueto a gradual increasing applied voltage, and curve 26 represents thedecrease in current due toa gradually decreasing applied voltage. Itwill be noted that the value of the voltage at which the currentrepresented by 26 suddenly decreases or the dissonant voltage ismaterially lower than the applied voltage at which the current suddenlyincreases, namely, the resonant voltage. Advantage is taken in the formof my invention shown in Fig. 3 of this difference in resonant anddissonant voltages of the non-linear resonant circuit 20. Thus when lamp7 is illuminated as a result of the decrease in impedance of reactor 10,the voltage applied to the non-linear resonant circuit must decreasefrom the resonant voltage to the dissonant voltage thereof before thecurrent supplied to the rectifier 12 of the first branch is decreasedsufiicient to substantially deenergize the saturating winding 11 of thereactor asso ciated therewith and thereby to cause the first lamp 4 tobe extinguished. Similarly when lamp 7 of the last branch is to beextinguished, the voltage applied to the non-linear resonant circuit 20must rise from the dissonant value to the resonant value beforesaturating current will be supplied to the reactor of the first branch.The sudden variations in current in the non-linear resonant circuit areprevented from causing any flicker of the lamps by the presence of thecapacitor 23 for the reason already described above.

Although I have chosen to illustrate my invention as having a smallnumber of branch load circuits the actual number of branch circuits usedmay be anything desired. The number may even be reduced to a single loadcircuit in which case the load, if a lamp, operates as a single flashinglight or beacon. Such a modification is shown by Fig. 5 where the periodof operation is controlled, for example, by the non-linear resonantcircuit 20 as in Fig. 3. While I have spoken of lamp 4 as being in thefirst branch of the series and of lamp '7 as being in the last branchthereof the series in reality is endless, the operation of lamp 4following that of lamp '7 after a somewhat greater delay than that afterthe operation of each of the other lamps.

For the sake of simplicity I have shown the saturable core reactors 10in a. purely diagrammatic manner. Their actual construction may, forexample, be as shown in Fig. 6 where the core of reactor 10 has fourlegs, the alternating current winding of which comprises the coils 27and 28 wound in opposite directions on the two inner legs of the coreand connected in parallel in the alternating current branch circuit andwhere the saturating winding 11 which comprises the single coil 29surrounds both of said legs. A reactor of this type is disclosed in theAlexanderson Patent No. 1,328,610, January 20, 1920. Instead of a singlecore reactor I may employ two separate transformers 30 and 31 as showndiagrammatically in Fig. '7. These transformers respectively havesaturating windings 32 and 33 which are shown connected in series andalternating current windings 34 and 35 shown connected in parallel.windings 34 and 35 are shown reversed in order to prevent alternatingcurrent from being introduced in the direct current circuit.

I have chosen the particular embodiments described above as illustrativeof my invention, and it will be apparent that various othermodifications may be made without departing from the spirit and scope ofmy invention, which modifications I aim to cover by the appended claims.

What I claim as new and desire to secure by Letters Patent in the UnitedStates is:

1. A sequence operating system comprising an alternating current supplycircuit, a series of branch circuits connected therewith, each includinga load device, time delay variable impedance means in each branchresponsive to the current in the preceding branch, and means providing agreater time delay responsive to the current in one branch of the seriesfor controlling the 1mpedance of another branch thereof.

2. A sequence operating system comprising an alternating current supplycircuit, a series of branch circuits connected therewith each includinga load device, a saturable core reactor in each branch circuit forvarying the current therein in response to the current in a precedingbranch circuit with a predetermined time delay and means responsive tothe current in one branch circuit for providing an additional time delayin the current variation in the next branch circuit of the series.

3. A sequence operating system comprising an alternating current supplycircuit, a series of branch circuits connected therewith each includinga load device, time delay means including a saturable core reactor ineach branch circuit for controlling the current therein, each reactorhaving a saturating winding responsive to the current in the precedingbranch of the series, and additional time delay means for controllingthe current in the saturating winding of the reactor in one branch ofthe series in accordance with the current in a preceding branch thereof.

4. A sequence operating system comprising an alternating current supplycircuit, a series of branch circuits connected therewith each includinga load device, a saturable core reactor in each branch circuitresponsive to the current of the preceding branch, anda relay responsiveto the current in the last branch of the series for controlling thereactor of the first branch.

5. A sequence operating system comprising an alternating current supplycircuit, a series of branch circuits connected therewith each includinga load device, a saturable core reactor in each branch circuitresponsive to the current of the preceding branch, and a relayresponsive to the current in the last branch of the series forcontrolling the reactor of the first branch, said relay having acapacitor connected across the winding thereof whereby the impedance ofthe relay in closed circuit position is the same as in open circuitposition.

6. A sequence operating system comprising an alternating current supplycircuit, a series of branch circuits connected therewith each includinga load device, a saturable core reactor in each branch circuitresponsive to the current of the preceding branch, and a non-linearresonant circuit responsive to the current in one branch of the seriesfor controlling the reactor of another branch.

7. A sequence operating system comprising an alternating current supplycircuit, a series of branch circuits connected therewith each includinga load device, a saturable core reactor in each branch circuitresponsive to the current of the preceding branch, a series non-linearresonant circuit connected across the reactor of the last branch forcontrolling the saturation of the reactor of the first branch.

8. A sequence. operating system comprising an alternating current supplycircuit, a series of branch circuits connected therewith each includinga load device, a saturable core reactor in each branch circuitresponsive to the current of the preceding branch, a non-linear resonantcircuit responsive to the current in the last branch of the series forcontrolling the reactor of the first branch, and a capacitor connectedacross said non-linear circuit whereby the impedance of the non-linearcircuit is the same whether the circuit is in resonant or non-reso-enant condition.

9. A sequence operating system comprising an alternating current supplycircuit, a series of branch circuits connected therewith each includin aload device, a saturable core' reactor in each branch circuit responsiveto the current of the preceding branch, a relay responsive to thecurrent in the last branch of the series for controlling the reactor oithe first branch, and a rectifier connecting the relay with said lastbranch.

10. In combination, an alternating current circuit, a saturable corereactor therein for con trolling the current flow in the circuit and arelay connected to be responsive to the voltage across said reactor forcontrolling the saturation thereof.

11. In combination, an alternating current circuit, variable impedancemeans therein for controlling the current in the circuit comprising asaturable core reactor having a saturating winding, and a relay having awinding connected across said reactor and having contacts arranged tocontrol the current in said saturating winding.

CHAUNCEY G. SUITS.

